Sending syslog from Linux systems into Graylog
The two most popular syslog deamons (the programs that run in the background to accept and write or forward logs) are rsyslog and syslog-ng. One of these will most likely be running on your Linux distribution. (Please refer to your distribution documentation if you are unsure)
rsyslog
Forwarding syslog messages with rsyslog is easy. The only important thing to get the most out of your logs is following
RFC 5424. The following examples configure your rsyslog daemon to send
RFC 5424 date to Graylog syslog inputs:
UDP:
*.* @graylog.example.org:514;RSYSLOG_SyslogProtocol23Format
TCP:
*.* @@graylog.example.org:514;RSYSLOG_SyslogProtocol23Format
(The difference between UDP and TCP is using @ instead of @@ as target descriptor.)
The above configuration should be placed as new file in /etc/rsyslog.d/ and rsyslog should be restarted. In addition the port 514 on the Graylog server need to be reachable from the sending server.
old rsyslog
If you're using a very old version of rsyslog (versions before rsyslog 5.10) which doesn't provide the built-in RSYSLOG_SyslogProtocol23Format template, you can create a custom message template.
For UDP this becomes:
$template GRAYLOGRFC5424,"<%PRI%>%PROTOCOL-VERSION% %TIMESTAMP:::date-rfc3339% %HOSTNAME% %APP-NAME% %PROCID% %MSGID% %STRUCTURED-DATA% %msg%\n"
*.* @graylog.example.org:514;GRAYLOGRFC5424
syslog-ng
Configuring syslog-ng to send syslog to Graylog is equally simple. Use the syslog function to send
RFC 5424 formatted syslog messages via TCP to the remote Graylog host:
# Define TCP syslog destination.
destination d_net {
syslog("graylog.example.org" port(514));
};
# Tell syslog-ng to send data from source s_src to the newly defined syslog destination.
log {
source(s_src); # Defined in the default syslog-ng configuration.
destination(d_net);
};
lennartkoopmann
free!
Just to mention that currently only legacy rsyslog syntax is documented,
the more modern approach would be:
action(type="omfwd" target="127.0.0.1" port="10514" template="RSYSLOG_SyslogProtocol23Format")